This invention relates to the field of high-power rescue tools. The invention provides a rescue tool which may be used with a variety of different sources of power, and which can be operated with great precision.
High-power rescue tools have been known for a long time. Examples of rescue tools are shown in U.S. Pat. Nos. 3,819,153, 4,392,263, and 4,531,289. The disclosures of the latter patents are incorporated by reference herein.
High-power rescue tools are used to extricate accident victims who are trapped within the wreckage of automobiles or other heavy vehicles. A rescue must be done rapidly, so that the victim can be quickly moved to a hospital. But speed is not enough; the rescue must also be done with sufficient care to prevent additional harm to the victim.
Rescue tools generally include a pair of arms, mounted to pivot around a common point of connection. The arms therefore move apart and together, under the influence of a driven piston. Most rescue tools include a pair of metal blades, attached to or forming part of the arms, the blades being sufficiently strong to cut through heavy metal. Opening and closing of the arms therefore enables the tool to cut like a scissors.
Rescue tools may also include other attachments. For example, some tools have a pair of work jaws attached to the ends of the arms. The work jaws can be used for prying, pulling, or lifting. The pulling function is accomplished by attaching cables to holes in the work jaws, so that movement of the arms pulls the cables with sufficient force to move a heavy object.
Most of the rescue tools of the prior art have been hydraulically powered. For example, U.S. Pat. No. 4,531,289 discloses a system of valves for directing hydraulic fluid to either side of a piston, thereby causing the arms of the tool to move apart or come together. Rescue tools have also been powered by pneumatically-driven motors, or by electric motors.
In general, each rescue tool of the prior art is specifically designed to be operated with only one kind of power source. For hydraulically-operated tools, it is usually necessary to provide a separate power unit, between the rescue tool and the reservoir of hydraulic fluid. It is difficult, if not impossible, to operate a rescue tool of the prior art with a power unit for which the tool was not originally intended.
Another disadvantage of rescue tools of the prior art is their lack of precision. When an accident victim is tightly trapped within the wreckage of an automobile, the process of extricating the victim often must be performed with surgical precision. A slight error in the movement of the arm can cause serious harm to the victim. It is not uncommon for the victim to survive the accident, but be endangered by a false motion of the tool. Thus, it is important that the cutting and prying be very precisely controllable.
Rescue tools of the prior art are not precision instruments. They are designed primarily to generate large cutting forces, but not to apply those forces in a controlled manner. The tools of the prior art are typically capable of generating very large forces, of the order of 40,000 pounds or more. When the power unit of such a tool is turned on, the arms will likely start to move with a jerk, and often overshoot their intended destination. It is therefore very difficult, if not impossible, to move the arm of a rescue tool, from a position of rest, through a short distance, in a controlled manner.
The present invention solves the above-described problems, by providing a tool in which the source of power is coupled to the arms by a threaded member. The threaded coupling makes the tool extremely versatile, as the tool can be powered by virtually any existing power source, without modifying the tool's internal structure. Also, the threaded coupling enables the tool to move with the precision necessary to prevent unintended harm to an accident victim.